1. Field of the Invention
The present invention relates to apparatuses and methods for processing video signals, for example, image pickup apparatuses and video playback apparatuses. More specifically, embodiments of the present invention relate to video systems in which a method of image-quality enhancement or playback-frame-rate conversion or other kind of processing is selected on the basis of a frame-rate conversion method of video signals. Embodiments of the present invention may advantageously be used where video signals are based on video content that has been picked up at speeds (frame rates) higher than standard broadcasting or recording frame rates.
2. Description of the Related Art
Recently, the image pickup speeds of image pickup elements are improving considerably. For example, an imaging element capable of picking up 180 image frames per second, with horizontally 1920 and vertically 1440 pixels per frame, has been made public.
With the current broadcasting standards, however, even with the high-definition standard, the imaging speed is 60 frames per second with horizontally 1920 and vertically 1080 pixels per frame. Thus, even if such a high-speed imaging element is used for image pickup, frame-rate conversion is needed for playback compliant with the standard.
As an example of related art relating to high-frame-rate image pickup and playback, according to Japanese Patent Laid-Open No. 2002-320203, at the time of high-frame-rate image pickup, video content is recorded at a standard frame rate suitable for a recording format, and information regarding an original frame rate is recorded in a separate area. At the time of playback, frame-rate conversion is executed according to the information to perform motion playback.
As another example, according to Japanese Patent Laid-Open No. 2006-025080, at the time of high-frame-rate image pickup, flags are attached to frames needed for playback at a standard frame rate, and playback is performed in accordance with the flags.
According to these techniques, since information regarding an original frame rate or the like is needed in order to suitably play back a moving picture that has been picked up, such information is additionally recorded.
Furthermore, as an example of techniques for attaching processing information, according to Japanese Patent Laid-Open No. 2005-252870, when the resolution of a compressed image is further reduced for re-compression, parameters indicating patterns for interpolation of lost high-frequency regions are additionally recorded, and the parameters are used for image-quality enhancement at the time of expansion of the re-compressed image.
Methods of achieving a desired frame rate through frame-rate conversion include a method in which one frame is generated by averaging a plurality of frames and a method in which one frame is generated by combining a plurality of frames in a complementary manner, and a method in which a desired frame rate is achieved by selecting frames with little blur.
A playback apparatus executes image-quality enhancement in a manner of its own on moving-picture data obtained through frame-rate conversion, and displays a playback image on a display. At this time, when the display uses its own frame rate, frame rate conversion is again executed at the display.
However, it has not been possible for the playback apparatus to recognize the type of frame-rate conversion executed on image data at the image pickup apparatus. Thus, there has been a possibility that the playback apparatus executes an undesired process that prohibits image-quality enhancement or that has little effect of image-quality enhancement during the course of image-quality-enhancement processes. Furthermore, there has been a possibility that the playback apparatus fails to execute playback at appropriate timing.